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Differential D25578 Diff 74909 head/sys/kern/vfs_lookup.c

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head/sys/kern/vfs_lookup.c

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#include <security/mac/mac_framework.h> #include <security/mac/mac_framework.h>
#include <vm/uma.h> #include <vm/uma.h>
#define NAMEI_DIAGNOSTIC 1 #define NAMEI_DIAGNOSTIC 1
#undef NAMEI_DIAGNOSTIC #undef NAMEI_DIAGNOSTIC
SDT_PROVIDER_DECLARE(vfs); SDT_PROVIDER_DECLARE(vfs);
SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *", SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *",
"unsigned long"); "unsigned long", "bool");
SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namei, lookup, return, "int", "struct vnode *", "bool");
/* Allocation zone for namei. */ /* Allocation zone for namei. */
uma_zone_t namei_zone; uma_zone_t namei_zone;
/* Placeholder vnode for mp traversal. */ /* Placeholder vnode for mp traversal. */
static struct vnode *vp_crossmp; static struct vnode *vp_crossmp;
static int static int
▲ Show 20 Lines • Show All 190 Lines • ▼ Show 20 Lines while (*(cnp->cn_nameptr) == '/') {
cnp->cn_nameptr++; cnp->cn_nameptr++;
ndp->ni_pathlen--; ndp->ni_pathlen--;
} }
*dpp = ndp->ni_rootdir; *dpp = ndp->ni_rootdir;
vrefact(*dpp); vrefact(*dpp);
return (0); return (0);
} }
/* static int
* Convert a pathname into a pointer to a locked vnode. namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
*
* The FOLLOW flag is set when symbolic links are to be followed
* when they occur at the end of the name translation process.
* Symbolic links are always followed for all other pathname
* components other than the last.
*
* The segflg defines whether the name is to be copied from user
* space or kernel space.
*
* Overall outline of namei:
*
* copy in name
* get starting directory
* while (!done && !error) {
* call lookup to search path.
* if symbolic link, massage name in buffer and continue
* }
*/
int
namei(struct nameidata *ndp)
{ {
char *cp; /* pointer into pathname argument */
struct vnode *dp; /* the directory we are searching */
struct iovec aiov; /* uio for reading symbolic links */
struct componentname *cnp; struct componentname *cnp;
struct file *dfp; struct file *dfp;
struct thread *td; struct thread *td;
struct proc *p;
struct pwd *pwd; struct pwd *pwd;
cap_rights_t rights; cap_rights_t rights;
struct filecaps dirfd_caps; struct filecaps dirfd_caps;
struct uio auio; int error, startdir_used;
int error, linklen, startdir_used;
cnp = &ndp->ni_cnd; cnp = &ndp->ni_cnd;
td = cnp->cn_thread; td = cnp->cn_thread;
p = td->td_proc;
ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
("namei: nameiop contaminated with flags"));
KASSERT((cnp->cn_flags & OPMASK) == 0,
("namei: flags contaminated with nameiops"));
MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
ndp->ni_startdir->v_type == VBAD);
TAILQ_INIT(&ndp->ni_cap_tracker);
ndp->ni_lcf = 0;
/* We will set this ourselves if we need it. */ *pwdp = NULL;
cnp->cn_flags &= ~TRAILINGSLASH;
/*
* Get a buffer for the name to be translated, and copy the
* name into the buffer.
*/
if ((cnp->cn_flags & HASBUF) == 0)
cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
if (ndp->ni_segflg == UIO_SYSSPACE)
error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
&ndp->ni_pathlen);
else
error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
&ndp->ni_pathlen);
/*
* Don't allow empty pathnames.
*/
if (error == 0 && *cnp->cn_pnbuf == '\0')
error = ENOENT;
#ifdef CAPABILITY_MODE #ifdef CAPABILITY_MODE
/* /*
* In capability mode, lookups must be restricted to happen in * In capability mode, lookups must be restricted to happen in
* the subtree with the root specified by the file descriptor: * the subtree with the root specified by the file descriptor:
* - The root must be real file descriptor, not the pseudo-descriptor * - The root must be real file descriptor, not the pseudo-descriptor
* AT_FDCWD. * AT_FDCWD.
* - The passed path must be relative and not absolute. * - The passed path must be relative and not absolute.
* - If lookup_cap_dotdot is disabled, path must not contain the * - If lookup_cap_dotdot is disabled, path must not contain the
* '..' components. * '..' components.
* - If lookup_cap_dotdot is enabled, we verify that all '..' * - If lookup_cap_dotdot is enabled, we verify that all '..'
* components lookups result in the directories which were * components lookups result in the directories which were
* previously walked by us, which prevents an escape from * previously walked by us, which prevents an escape from
* the relative root. * the relative root.
*/ */
if (error == 0 && IN_CAPABILITY_MODE(td) && if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) {
(cnp->cn_flags & NOCAPCHECK) == 0) {
ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
if (ndp->ni_dirfd == AT_FDCWD) { if (ndp->ni_dirfd == AT_FDCWD) {
#ifdef KTRACE #ifdef KTRACE
if (KTRPOINT(td, KTR_CAPFAIL)) if (KTRPOINT(td, KTR_CAPFAIL))
ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL);
#endif #endif
error = ECAPMODE; return (ECAPMODE);
} }
} }
#endif #endif
if (error != 0) { error = 0;
namei_cleanup_cnp(cnp);
ndp->ni_vp = NULL;
return (error);
}
ndp->ni_loopcnt = 0;
#ifdef KTRACE
if (KTRPOINT(td, KTR_NAMEI)) {
KASSERT(cnp->cn_thread == curthread,
("namei not using curthread"));
ktrnamei(cnp->cn_pnbuf);
}
#endif
/* /*
* Get starting point for the translation. * Get starting point for the translation.
*/ */
pwd = pwd_hold(td); pwd = pwd_hold(td);
/* /*
* The reference on ni_rootdir is acquired in the block below to avoid * The reference on ni_rootdir is acquired in the block below to avoid
* back-to-back atomics for absolute lookups. * back-to-back atomics for absolute lookups.
*/ */
ndp->ni_rootdir = pwd->pwd_rdir; ndp->ni_rootdir = pwd->pwd_rdir;
ndp->ni_topdir = pwd->pwd_jdir; ndp->ni_topdir = pwd->pwd_jdir;
startdir_used = 0;
dp = NULL;
cnp->cn_nameptr = cnp->cn_pnbuf;
if (cnp->cn_pnbuf[0] == '/') { if (cnp->cn_pnbuf[0] == '/') {
ndp->ni_resflags |= NIRES_ABS; ndp->ni_resflags |= NIRES_ABS;
error = namei_handle_root(ndp, &dp); error = namei_handle_root(ndp, dpp);
} else { } else {
if (ndp->ni_startdir != NULL) { if (ndp->ni_startdir != NULL) {
dp = ndp->ni_startdir; *dpp = ndp->ni_startdir;
startdir_used = 1; startdir_used = 1;
} else if (ndp->ni_dirfd == AT_FDCWD) { } else if (ndp->ni_dirfd == AT_FDCWD) {
dp = pwd->pwd_cdir; *dpp = pwd->pwd_cdir;
vrefact(dp); vrefact(*dpp);
} else { } else {
rights = ndp->ni_rightsneeded; rights = ndp->ni_rightsneeded;
cap_rights_set_one(&rights, CAP_LOOKUP); cap_rights_set_one(&rights, CAP_LOOKUP);
if (cnp->cn_flags & AUDITVNODE1) if (cnp->cn_flags & AUDITVNODE1)
AUDIT_ARG_ATFD1(ndp->ni_dirfd); AUDIT_ARG_ATFD1(ndp->ni_dirfd);
if (cnp->cn_flags & AUDITVNODE2) if (cnp->cn_flags & AUDITVNODE2)
AUDIT_ARG_ATFD2(ndp->ni_dirfd); AUDIT_ARG_ATFD2(ndp->ni_dirfd);
Show All 10 Lines if (ndp->ni_startdir != NULL) {
* safely returned to the caller. * safely returned to the caller.
*/ */
} else { } else {
if (dfp->f_ops == &badfileops) { if (dfp->f_ops == &badfileops) {
error = EBADF; error = EBADF;
} else if (dfp->f_vnode == NULL) { } else if (dfp->f_vnode == NULL) {
error = ENOTDIR; error = ENOTDIR;
} else { } else {
dp = dfp->f_vnode; *dpp = dfp->f_vnode;
vrefact(dp); vrefact(*dpp);
if ((dfp->f_flag & FSEARCH) != 0) if ((dfp->f_flag & FSEARCH) != 0)
cnp->cn_flags |= NOEXECCHECK; cnp->cn_flags |= NOEXECCHECK;
} }
fdrop(dfp, td); fdrop(dfp, td);
} }
#ifdef CAPABILITIES #ifdef CAPABILITIES
/* /*
* If file descriptor doesn't have all rights, * If file descriptor doesn't have all rights,
* all lookups relative to it must also be * all lookups relative to it must also be
* strictly relative. * strictly relative.
*/ */
CAP_ALL(&rights); CAP_ALL(&rights);
if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights, if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights,
&rights) || &rights) ||
ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL || ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
ndp->ni_filecaps.fc_nioctls != -1) { ndp->ni_filecaps.fc_nioctls != -1) {
ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
} }
#endif #endif
} }
if (error == 0 && dp->v_type != VDIR) if (error == 0 && (*dpp)->v_type != VDIR)
error = ENOTDIR; error = ENOTDIR;
} }
if (error == 0 && (cnp->cn_flags & BENEATH) != 0) { if (error == 0 && (cnp->cn_flags & BENEATH) != 0) {
if (ndp->ni_dirfd == AT_FDCWD) { if (ndp->ni_dirfd == AT_FDCWD) {
ndp->ni_beneath_latch = pwd->pwd_cdir; ndp->ni_beneath_latch = pwd->pwd_cdir;
vrefact(ndp->ni_beneath_latch); vrefact(ndp->ni_beneath_latch);
} else { } else {
rights = ndp->ni_rightsneeded; rights = ndp->ni_rightsneeded;
cap_rights_set_one(&rights, CAP_LOOKUP); cap_rights_set_one(&rights, CAP_LOOKUP);
error = fgetvp_rights(td, ndp->ni_dirfd, &rights, error = fgetvp_rights(td, ndp->ni_dirfd, &rights,
&dirfd_caps, &ndp->ni_beneath_latch); &dirfd_caps, &ndp->ni_beneath_latch);
if (error == 0 && dp->v_type != VDIR) { if (error == 0 && (*dpp)->v_type != VDIR) {
vrele(ndp->ni_beneath_latch); vrele(ndp->ni_beneath_latch);
error = ENOTDIR; error = ENOTDIR;
} }
} }
if (error == 0) if (error == 0)
ndp->ni_lcf |= NI_LCF_LATCH; ndp->ni_lcf |= NI_LCF_LATCH;
} }
/* /*
* If we are auditing the kernel pathname, save the user pathname. * If we are auditing the kernel pathname, save the user pathname.
*/ */
if (cnp->cn_flags & AUDITVNODE1) if (cnp->cn_flags & AUDITVNODE1)
AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, dp, cnp->cn_pnbuf); AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
if (cnp->cn_flags & AUDITVNODE2) if (cnp->cn_flags & AUDITVNODE2)
AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, dp, cnp->cn_pnbuf); AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
if (ndp->ni_startdir != NULL && !startdir_used) if (ndp->ni_startdir != NULL && !startdir_used)
vrele(ndp->ni_startdir); vrele(ndp->ni_startdir);
if (error != 0) { if (error != 0) {
if (dp != NULL) if (*dpp != NULL)
vrele(dp); vrele(*dpp);
goto out; return (error);
} }
MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) != MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) !=
NI_LCF_BENEATH_ABS); NI_LCF_BENEATH_ABS);
if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 && if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 &&
lookup_cap_dotdot != 0) || lookup_cap_dotdot != 0) ||
((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 && ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 &&
(cnp->cn_flags & BENEATH) != 0)) (cnp->cn_flags & BENEATH) != 0))
ndp->ni_lcf |= NI_LCF_CAP_DOTDOT; ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
SDT_PROBE3(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf, SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
cnp->cn_flags); cnp->cn_flags, false);
*pwdp = pwd;
return (0);
}
/*
* Convert a pathname into a pointer to a locked vnode.
*
* The FOLLOW flag is set when symbolic links are to be followed
* when they occur at the end of the name translation process.
* Symbolic links are always followed for all other pathname
* components other than the last.
*
* The segflg defines whether the name is to be copied from user
* space or kernel space.
*
* Overall outline of namei:
*
* copy in name
* get starting directory
* while (!done && !error) {
* call lookup to search path.
* if symbolic link, massage name in buffer and continue
* }
*/
int
namei(struct nameidata *ndp)
{
char *cp; /* pointer into pathname argument */
struct vnode *dp; /* the directory we are searching */
struct iovec aiov; /* uio for reading symbolic links */
struct componentname *cnp;
struct thread *td;
struct proc *p;
struct pwd *pwd;
struct uio auio;
int error, linklen;
enum cache_fpl_status status;
cnp = &ndp->ni_cnd;
td = cnp->cn_thread;
p = td->td_proc;
ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred;
KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc"));
KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0,
("namei: nameiop contaminated with flags"));
KASSERT((cnp->cn_flags & OPMASK) == 0,
("namei: flags contaminated with nameiops"));
MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
ndp->ni_startdir->v_type == VBAD);
TAILQ_INIT(&ndp->ni_cap_tracker);
ndp->ni_lcf = 0;
ndp->ni_loopcnt = 0;
dp = NULL;
/* We will set this ourselves if we need it. */
cnp->cn_flags &= ~TRAILINGSLASH;
ndp->ni_vp = NULL;
/*
* Get a buffer for the name to be translated, and copy the
* name into the buffer.
*/
if ((cnp->cn_flags & HASBUF) == 0)
cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
if (ndp->ni_segflg == UIO_SYSSPACE)
error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
&ndp->ni_pathlen);
else
error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN,
&ndp->ni_pathlen);
if (error != 0) {
namei_cleanup_cnp(cnp);
return (error);
}
cnp->cn_nameptr = cnp->cn_pnbuf;
/*
* Don't allow empty pathnames.
*/
if (*cnp->cn_pnbuf == '\0') {
namei_cleanup_cnp(cnp);
return (ENOENT);
}
#ifdef KTRACE
if (KTRPOINT(td, KTR_NAMEI)) {
KASSERT(cnp->cn_thread == curthread,
("namei not using curthread"));
ktrnamei(cnp->cn_pnbuf);
}
#endif
/*
* First try looking up the target without locking any vnodes.
*
* We may need to start from scratch or pick up where it left off.
*/
error = cache_fplookup(ndp, &status, &pwd);
switch (status) {
case CACHE_FPL_STATUS_UNSET:
__assert_unreachable();
break;
case CACHE_FPL_STATUS_HANDLED:
return (error);
case CACHE_FPL_STATUS_PARTIAL:
dp = ndp->ni_startdir;
break;
case CACHE_FPL_STATUS_ABORTED:
error = namei_setup(ndp, &dp, &pwd);
if (error != 0) {
namei_cleanup_cnp(cnp);
return (error);
}
break;
}
/*
* Locked lookup.
*/
for (;;) { for (;;) {
ndp->ni_startdir = dp; ndp->ni_startdir = dp;
error = lookup(ndp); error = lookup(ndp);
if (error != 0) if (error != 0)
goto out; goto out;
/* /*
* If not a symbolic link, we're done. * If not a symbolic link, we're done.
*/ */
if ((cnp->cn_flags & ISSYMLINK) == 0) { if ((cnp->cn_flags & ISSYMLINK) == 0) {
if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
namei_cleanup_cnp(cnp); namei_cleanup_cnp(cnp);
} else } else
cnp->cn_flags |= HASBUF; cnp->cn_flags |= HASBUF;
if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS |
NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) { NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) {
NDFREE(ndp, 0); NDFREE(ndp, 0);
error = ENOTCAPABLE; error = ENOTCAPABLE;
} }
nameicap_cleanup(ndp, true); nameicap_cleanup(ndp, true);
SDT_PROBE2(vfs, namei, lookup, return, error, SDT_PROBE3(vfs, namei, lookup, return, error,
(error == 0 ? ndp->ni_vp : NULL)); (error == 0 ? ndp->ni_vp : NULL), false);
pwd_drop(pwd); pwd_drop(pwd);
return (error); return (error);
} }
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP; error = ELOOP;
break; break;
} }
#ifdef MAC #ifdef MAC
▲ Show 20 Lines • Show All 58 Lines • ▼ Show 20 Lines#endif
} }
vput(ndp->ni_vp); vput(ndp->ni_vp);
ndp->ni_vp = NULL; ndp->ni_vp = NULL;
vrele(ndp->ni_dvp); vrele(ndp->ni_dvp);
out: out:
MPASS(error != 0); MPASS(error != 0);
namei_cleanup_cnp(cnp); namei_cleanup_cnp(cnp);
nameicap_cleanup(ndp, true); nameicap_cleanup(ndp, true);
SDT_PROBE2(vfs, namei, lookup, return, error, NULL); SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false);
pwd_drop(pwd); pwd_drop(pwd);
return (error); return (error);
} }
static int static int
compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags)
{ {
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